Vitamin D and Asthma, a reviewIn the last 40 years a progresive decrease of vitamin D levels has been observed in the population due to changes in lifestyles.Low levels of vitamin D have been associated with several diseases, including asthma.Recent studies have shown that low levels of vitamin D in children are correlated with an increase in bronchial reactivity and atopia.In children with an established diagnosis of asthma, low levels of vitamin D is associated with a more severe evolution of asthma, including increased numbers of emergency room visits and hospital admissions, low lung function, increased use of inhaled and systemic corticosteroids and more frequent and severe exacerbations.The role of vitamin D on bronquial asthma is its immunomodulatory action upon the cells of the immune system, inhibiting Th2 type cytokines and IL17 secretion and stimulating IL 10 secretion.In vitro studies suggest a posible role of vitamin D in reverting steroid resistance and airways remodeling.